In the field of aeronautics, a cyclic stick refers to a control device for the pilot to enable turns and forward power of an aircraft, particularly a helicopter. The cyclic stick typically uses a force gradient mechanism so that the amount of force applied to the cyclic stick translates into the desired control feel. A typical force gradient incorporates a spring that compresses as the pilot applies force to the cyclic stick. As the pilot increases the force applied to the cyclic stick, the spring compresses more and the control input becomes greater in magnitude.
Modern helicopters are equipped with an automatic flight control system (AFCS) and can be flown by either the manual input of the pilot or the AFCS. Typically, there is no automatic control to turn on and off the AFCS, and the input from the cyclic stick signals the pilot's intention to take over the control. In order to correctly interpret the pilot's intention, there must be a mechanism to determine whether or not the input received from the cyclic is indeed caused by the pilot or by an unintended change in flight conditions such as a wind gust, shift of center of gravity (CG), etc.
Traditional force gradient switches utilize a mechanical actuator mechanism to control the operation of an AFCS. The mechanical actuator mechanism requires frequent adjustment to maintain proper operating conditions. Oftentimes, the adjustment or maintenance requires disassembling the force gradient to gain access and service the inner parts. Due to such issues and inconveniences associated with the mechanical switch design, there is a need for a more convenient yet reliable solution that provides benefits over the conventional force gradient design.